Welcome to Proj4js

Proj4js is a JavaScript library to transform point coordinates from one coordinate system to another, including datum transformations.

This library is a port of both the ​PROJ.4 and ​GCTCP C libraries to JavaScript. Enabling these transformations in the browser allows geographic data stored in different projections to be combined in browser-based web mapping applications.

Proj4js is a part of the ​MetaCRS group of projects.

Starting Points

• Download -- Get Proj4js now!
• UserGuide -- User documentation - how to use Proj4js
• Examples -- Examples of Proj4js in use
• MailingList -- Mailing lists and contact info
• DevGuide -- Developer documentation
• Primer -- Coordinate Systems Primer